The instant invention relates to applicant's issued U.S. Pat. Nos. 4,927,430 and 5,136,808 . The method herein disclosed is a new and continuous process to upgrade residuum and heavy crude oil without producing by-product coke or other waste. In addition, oily refinery wastes (U.S. EPA designated "K-Wastes") can be co-processed yielding valuable, non-hazardous products. The method is a closed system and is thermally self-sufficient.
The crude oil available to refiners is becoming heavier and declining in quality; further the sulfur content in the crude is on the increase. This causes the production of vast quantities of a by-product called "residuum," a low value, asphalt-like residual material which is becoming difficult to market. Conventionally the residuum is mixed with a high value cutter stock (thinner) and converted to residual fuel oil. The residual fuel oil possesses excessive quantities of sulfur which makes this fuel, when combusted, unacceptable to current and foreseeable environmental standards. The World Bank, in its Technical Paper Number 32, entitled "World Refinery Industry--Need for Restructuring," page 120, paragraph 7.23, states the following: ". . . there will be substantial deficits in middle distillates, and large surplus of residual fuel oil."
The U.S. Department of Energy (DOE), in its Program Solicitation DE-PS22-92BC14809 issued on Dec. 11, 1991, pages 1 and 2, paragraphs 4 and 1 respectively, is encouraging the development of ". . . better ways to convert heavy crude oil and the residuum fraction of conventional crudes to high quality light products." Further, the U.S. DOE's objective is to ". . . increase the use of residuum and heavier hydrocarbon feedstock in the production of light, environmentally acceptable fuels, by increasing process yield and reducing carbon rejection in the form of coke. This research is essential to the efficient upgrading and processing of heavy hydrocarbons."
In conventional practice residuum (hereinafter referred to as "resid") is coked to produce petroleum coke in a "Delayed Coker" which is the process most widely used. However, as stated above, the goal is not to reject carbon in the form of coke because petroleum coke has high sulfur and heavy metals and therefore there is no market for it. A process known as "Flexicoking," which is proprietary of Exxon, uses fluidized bed coking integrated to coke gasification. The disadvantages of the Flexicoke process are as follows:
It does not provide for variable temperature control in the reactor to process a wide range of resids and crudes; PA1 Steam is injected into the reactor; PA1 Requires a gas plant to separate the complicated mixture of C.sub.1 to C.sub.4 hydrocarbons; PA1 Does not produce directly clean gas which is rich in H.sub.2 needed in hydro-processing; PA1 Cannot produce syngas (CO+H.sub.2) without a dual gasification; PA1 Does not produce a vitrified slag which is inert; PA1 Does not treat the gas produced for sulfur removal while the gas is hot; PA1 Uses steam in the gasification step to moderate temperature in gasifier; PA1 Does not co-feed a desulfurizer with the resid; PA1 Uses a scrubber; PA1 Circulates reactor coke to a heater for temperature pickup; PA1 Is not modular in construction.
With the above and other considerations in view, the main object of this invention is to provide a new, improved and continuous method to upgrade resid and heavy crude oil to produce lighter liquids economically and in an environmentally acceptable manner.
Still an object of the present invention is to provide a method that is efficient in heat transfer when processing the resid or crude oil.
Therefore an object of the present invention is to provide a method that is adapted to control the temperature when processing the resid or crude oil in order to make possible the processing of a wide range of resids and crudes.
Yet an object of the instant invention is to provide an improved method which is capable of processing resids and crudes without the implementation of steam during the coking step or during the gasification of the carbon.
Another object of the instant invention is to provide a method that requires no gas plant to separate the complicated mixture of C.sub.1 to C.sub.4 hydrocarbons by directly producing a clean hydrogen-rich gas without the use of a dual gasification step.
Still another object of the present invention is to provide a method that produces no ash but a vitrified inert slag which can be used for road ice control or abrasives and which will not leach.
Therefore another object of the present invention is to provide a method that treats the gas produced for sulfur removal in a hot gas cleanup.
Yet another object of this invention is to provide a method that is capable of processing resids and crudes while co-feeding the resids and crudes with a sulfur treating sorbent to further enhance the removal of sulfur.
Yet still another object of the present invention is to provide a method wherein the application of heat to the resid or crude oil for the rejection of carbon is carried out in such a way as to cause the rapid and efficient formation of carbon upon a heated surface and the stripping (removal) of said carbon from said surface in order to provide a freshly exposed heated surface for the additional application of resid or crude on said heated surface for the further rejection of additional carbon in a rapid and efficient manner, said rejected carbon being subsequently gasified to produce a gas which is treated for sulfur removal.
It is still another object of the present invention to provide a method wherein the hydrogen-rich gas produced is recycled for the treatment or hydro-cracking of the lighter liquids produced.
It is therefore another object of the present invention to provide a modular construction in order to make scale-up of the method predictable.
It is yet another object of the instant invention to provide a method that contains the above mentioned advantages and still requires a relatively low capital investment.
The above and other objects of the instant invention will become more apparent to those skilled in the art to which this invention pertains and particularly from the following description.